While much of the recent attention on drug abuse in the United States has focused on the heroin and opioid epidemic, cocaine has also been making a comeback. It appears to be a case of supply driving demand.

After years of falling output, the size of Colombia’s illegal coca crop has exploded since 2013, and the boom is starting to appear on U.S. streets.

“There are troubling early signs that cocaine use and availability is on the rise in the United States for the first time in nearly a decade,” the State Department noted this week in its annual report on the global narcotics trade.

According to test samples of the drug seized on the streets, 90 percent of the cocaine for sale in the United States is of Colombian origin, according to the report.

The number of overdose deaths in the United States involving cocaine in 2015 was the highest since 2006 and the second-highest since 1999, the federal Substance Abuse and Mental Health Services Administration reported in December.

And the number of young Americans who admitted to trying cocaine for the first time increased a whopping 61 percent from 2013 to 2015, the most recent National Survey on Drug Use and Health found.

According to that survey, 1 in 20 American adults ages 18 to 25 used the drug in 2015, with the highest percentage concentrated in the Northeast. In New Hampshire, more than 10 percent of young adults used cocaine in 2015.

This surge in consumption can be traced directly to Colombia’s bumper harvest. The country’s illegal coca crop doubled between 2013 and 2015, reaching nearly 400,000 acres. That’s almost twice as much as the combined output of Peru and Bolivia, the world’s second- and third-largest producers.

Cocaine trafficking from Colombia is at “record levels,” the State Department acknowledged this week in its report, warning that even bigger loads are probably on the way. Although data for last year is not yet available, “the preliminary estimated coca cultivation and cocaine production figures for 2016 indicate a dramatic increase in cultivation and cocaine production,” the report said.

“Due to the lag time between coca cultivation and cocaine distribution, the full impact of this surge in coca cultivation likely remains to materialize,” the report added.

U.S. officials have been watching Colombia’s coca-growing bonanza with rising alarm in recent years, but they generally refrained from criticizing the country too loudly at a time when President Juan Manuel Santos was engaged in sensitive peace talks with the leftist FARC rebels who dominated the drug trade.

Since 2000, the United States has sent Bogota more than $10 billion in counternarcotics and security assistance through “Plan Colombia.” That congressional funding is widely credited with helping tip Colombia’s 52-year civil conflict in the government’s favor and forcing FARC to the bargaining table. A final peace accord was signed in November, and the rebels have moved into temporary camps where they have started handing over their weapons to the United Nations.

The State Department report praises the Colombian government as a faithful and determined partner in the drug war fight, noting that narcotics seizures in the country are also at record highs.

Speaking to reporters this week, the head of the State Department’s Bureau of International Narcotics and Law Enforcement Affairs, Assistant Secretary William Brownfield, said that Colombia remains “the government with which we have perhaps the closest relationship here in the Western Hemisphere over the past 17 years.”

“We are working the problem. It is a serious problem. Both governments recognize this fact,” said Brownfield, who added that he is planning to travel to Bogota next week for meetings with Colombian officials.

“Both governments realize that it is neither in the interest of Colombia, nor in the United States of America, nor, frankly, any country in the Western Hemisphere or the world, that there be more than a doubling of cocaine production,” he said.

The State Department report cites four major reasons for the sudden coca-growing binge by Colombian farmers.

The first is that FARC rebels appear to have encouraged farmers in areas under their control to plant as much coca as possible in preparation for the end of the war, “purportedly motivated by the belief that the Colombian government’s post-peace accord investment and subsidies will focus on regions with the greatest quantities of coca,” the report said.

At the same time, the government reduced eradication in those areas “to lower the risk of armed conflict” and create a favorable climate for the final peace settlement.

The Colombian government also ended aerial spraying with herbicides in favor of manual eradication. But when eradication brigades have arrived to tear out illegal crops, local farmers have blocked roads and found other ways to thwart the removal, including the placement of improvised explosive devices among the coca bushes.

The final factor is the Colombian government’s financial squeeze, “resulting in a 90 percent reduction in the number of manual eradicators in 2016 as compared to 2008,” according to the report.

President Barack Obama had proposed nearly $450 million in security aid to Colombia this year to support implementation of its peace deal with the FARC rebels, a more than 40 percent increase. But Congress has yet to approve the funds, and many critics are frustrated by the huge setback to formerly successful joint efforts against cocaine production and trafficking.

Most of the Colombian cocaine is smuggled through Mexico by the country’s powerful drug cartels. Although President Trump has touted his plans for a wall along the Mexico border as a solution to the problem, narcotics agents say high-value, low-volume drugs such as cocaine are rarely brought into the country by couriers sneaking through the desert or wading across the Rio Grande.

Instead, the drugs are typically smuggled in high-powered speedboats, in vehicles with hidden compartments that cross the border at legal ports of entry, or by people carrying them in their abdominal cavities.